Drying of foodstuffs is primarily done in an effort to preserve food for future use, or to convert one foodstuff into another. Many different methods and apparatuses have been developed to dry food, but one problem with drying food is preserving a desired food quality in the final product. Other than nutritional value, the quality most desired to be preserved is usually taste.
In the wine industry, berries may be first dried to reduce their moisture content. A berry is a fleshy fruit produced from a single ovary. Grapes are an example. The drying process concentrates and develops aromatic compounds, sugars and polyphenols in the berries. When the berries are sufficiently dry, they are further processed into wine.
Withering of berries can be achieved by over-ripening of the berries in the field either on or off the vines, or indoors under fully or partially controlled condition. Clusters of berries are typically placed on trays in a single layer. The structure and openings of the trays are important factors in facilitating air movement through and around the berry clusters, and also play an important role in preventing the growth of undesirable mold. The drying process can last up to 120 days and berries are usually crushed when they have lost 30% to 40% of their original weight.
Appassimento drying is a particular process developed in Italy, which occurs in dedicated lofts called fruttaio under specific environmental conditions and through an established method. In Appassimento wine production there are two lines of thought: the traditional method where natural drying conditions are an essential requirement; or new system designs by which postharvest stresses must be controlled and recorded. The main environmental conditions which are considered during drying are the temperature and the relative humidity (RH), which affect respiration rate. Airflow may also play a role. Certainly, in the traditional method, the day/night environmental variations are considered fundamental, as well as the specific containers used to hold the berries.
Traditional Italian wines made using the Appassimento method, such as Amarone, Recioto and Ripasso, command premium prices. However, wine makers in North American regions, for example Ontario, have difficulty creating wines using the Appassimento drying method due to inconsistent results, losses from mold and the labor intensive nature of the traditional Appassimento drying method. In order to take advantage of the market niche for wines made using the Appassimento drying method, it would be desirable to have a method by which berries may be dried to achieve the same or similar result as the traditional Appassimento method.